Wearable Pulse Oximeter Spring Mechanism for PPG Signal Quality
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Solution Overview
Problem
Existing health monitoring devices face challenges in miniaturization, particularly with blood pressure cuff measurements, and require multiple devices for pulse transit time measurement, limiting mobility and continuous monitoring capabilities.
Innovation Solution
A wearable patch with a mechanical spring mechanism for intimate pulse oximeter contact, combined with EKG electrodes and accelerometry, allowing for continuous EKG and PPG data collection without user intervention, enabling real-time data transmission and estimation of blood pressure through pulse transit time calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard blood pressure cuff is used for measurement, then measurement accuracy is improved, but device portability and miniaturization deteriorate
Solution Approach 1:
The patent replaces the mechanical blood pressure cuff system with an optical-electrical measurement system. Instead of using an inflatable cuff to mechanically compress the arm, the invention uses photoplethysmography (optical sensors detecting blood volume changes) combined with electrocardiography (electrical heart activity detection) to measure pulse transit time, which correlates with blood pressure. This substitution eliminates the need for bulky mechanical components while maintaining measurement capability.
Solution Approach 2:
The wearable device performs multiple functions simultaneously: it measures pulse transit time for blood pressure estimation, monitors heart rate through EKG, and tracks physical activity via accelerometry. By consolidating these functions into a single lightweight device, the patent achieves both portability and comprehensive health monitoring without requiring separate specialized equipment for each measurement type.
2Measurement precision
If two separate pulse oximeter devices are used for upstream and downstream measurements, then pulse transit time measurement is enabled, but device complexity and ease of operation deteriorate
Solution Approach 1:
The patent combines the upstream (EKG electrode detecting electrical heartbeat) and downstream (pulse oximeter detecting pulsatile blood flow) measurement capabilities into a single integrated wearable device. The EKG electrode and pulse oximeter sensors are positioned on the same device body, allowing simultaneous acquisition of both signals needed for pulse transit time calculation without requiring the user to operate or coordinate multiple separate devices.
Solution Approach 2:
The single wearable device performs multiple measurement functions: EKG for electrical heartbeat detection, PPG for pulsatile flow detection, and accelerometry for motion tracking. This multi-functional integration enables the device to independently complete the entire pulse transit time measurement process without requiring additional specialized equipment, simplifying both the system architecture and user operation.
3Measurement precision
If a clip-style pulse oximeter is used for good skin contact, then PPG measurement quality is improved, but user mobility and ease of operation deteriorate
Solution Approach 1:
The patent employs a flexible, thin-film wearable design that conforms to the body contour. The pulse oximeter and EKG electrodes are integrated into a flexible substrate that can be comfortably worn against the skin, providing sustained intimate contact for high-quality optical and electrical signal acquisition without restricting user movement or requiring frequent adjustment like rigid clip-style devices.
Solution Approach 2:
The wearable device enables continuous, uninterrupted monitoring of PPG and EKG signals during normal daily activities. The flexible design maintains consistent skin contact throughout movement, allowing the device to continuously capture physiological data without requiring the user to stop, adjust the device, or remove it, thereby achieving both measurement quality and operational ease.
4Weight of moving object
If a wristwatch device is used for EKG measurement, then portability is improved, but measurement reliability deteriorates due to voluntary movement requirements
Solution Approach 1:
The wearable device automatically performs EKG measurements without requiring user initiation or voluntary action. The EKG electrodes continuously detect electrical heart activity as soon as the device is worn, eliminating the need for the user to deliberately position hands or activate the measurement function. This autonomous operation ensures reliable continuous monitoring even when the user is sleeping, has limited mobility, or is otherwise unable to voluntarily cooperate with the measurement process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides continuous, mobile health monitoring, increasing user mobility and reducing the need for frequent doctor visits, applicable for various applications including remote health care and sports monitoring, while achieving high-quality data collection without the need for multiple devices.
Implementation Method 1
use of a mechanical spring mechanism that can strongly press the pulse oximeter into the body
Implementation Method 2
PPG to optically measure the pulsatile flow that arrives at the fingers
Implementation Method 3
EKG to detect the instantaneous electrical heartbeat
Implementation Method 4
PTT is the time it takes a pressure wave to travel from the heart, or a point near the heart, to some other point downstream in the blood
Data Source
AI summary
A wearable electronic device comprises a base for mounting a plurality of sensors, where the sensors acquiring physiological data of a user wearing the device. By providing multiple sensors on a single device, additional physiological data, such as pulse transit time, can be provided. To ensure quality data is collected, the device includes a spring mechanism for applying a compressive force on the sensor to force it into the skin of a user.